1. Field of the Invention
This invention relates to a fabricating method for charge coupled device (CCD) channel by self-alignment, particularly to the method for fabricating the CCD channel which an enhancement of charge transfer efficiency can be obtained in case that small amount of charge exist in a CCD channel.
2. Description of Related Art
FIGS. 1A-1C show the configuration of a conventional CCD channel. As shown in these figures, the CCD channel consists of first polysilicon gates(2 and 2a) and second polysilicon gates(5 and 5a) which are placed alternatively. With this scheme, two-phase clock is necessary for the charge transfer.
However, conventional CCD channel structures have a critical shortcoming which is a poor charge transfer efficiency when a small amount of charge exists in the channel. This is because conventional CCD channels are laterally too wide for small amount charge which diffuse over the channel as shown in FIG. 1C, reducing self-induced field and fringing field. Consequently, charge transfer efficiency becomes degraded.